Cars are equipped with the following systems:
– speed control, which allows you to maintain the speed selected by the driver
This feature can be disabled at any time by pressing the brake pedal or one of the system switches.
– speed limit, which allows the driver to set a speed limit.
If it is exceeded, the impact on the accelerator pedal does not increase the speed of the car.
The selected speed can be increased at any time by pressing the accelerator pedal over the point of resistance.
Block diagram of the speed control and limiting system: 1 - switch (regulator) of the speed limiter; 2 - switches on the steering wheel; 3 - accelerator pedal; 4 - instrument panel; 5 - clutch travel sensor (if installed); 6 - stoplight switch; 7 - central electronic switching unit in the cabin; 8 - ABS computer; 9 - Injection computer
The "Speed control" and "Speed limit" functions are controlled by the injection computer.
This unit communicates with the ABS ECU, the UCH, the automatic transmission ECU (if installed) and the instrument panel.
The injection computer implements the setpoints by issuing control commands to the servo throttle valve or by adjusting the diesel fuel supply.
Description of system operation
The UCH sends "brake pedal depressed" information (signal from the brake light switch make contact). The ABS ECU sends information about the vehicle's speed.
The automatic transmission ECU (if equipped) sends information about the gear engaged.
The instrument panel displays the selected speed (variable or limited) and the function enabled symbol (tricolor warning light).
Each time these functions are activated, the on-board computer display switches to the corresponding page.
NOTE A fault warning light is not provided for the hold and speed limit functions.
Controls
A three-position switch enables or disables the governor or speed limiter.
The switches on the steering wheel are used to change the set speed, cancel a function, or recall a speed value from memory.
Accelerator pedal position sensor and brake light switch are used in common with the injection system.
The clutch pedal travel sensor is designed specifically for the cruise control function.
This sensor can also be used by the injection system.
The car has two clutch pedal position sensors: for starting the car from a stop (sensor for the end of the pedal travel) and for the speed control system (sensor for the start of the pedal travel).
The accelerator pedal has a safety switch at the end of travel.
Injection ECU
Injection control unit receives via multiplex network:
- – vehicle speed information (from ABS ECU);
- – signal from the make contact of the brake light switch (from the UCH);
- - information about the gear engaged (from the automatic transmission computer, if installed).
The injection computer sends over the multiplex network:
- – set value of adjustable or limited speed to the instrument panel;
- – a signal to turn on a two-color signal lamp on the instrument panel with a constant or flashing light;
- - control commands to the throttle valve with a servo or to the diesel fuel supply regulator;
- – information about automatic transmission gear shifting (if it is installed).
The injection computer receives information via wire:
- - from the accelerator pedal position sensor;
- - from the brake light switch (has two contacts: opening and closing);
- - from the clutch pedal travel sensor (if any);
- – three-position switch signal;
- - from the controls on the steering wheel.
Speed limiter
Inclusion conditions:
- - switch in the "speed limiter" position (30 km/h - minimum speed, 200 km/h - maximum speed);
- - pressing the switches "+", "-" or "R".
Shutdown conditions:
- - a sharp press on the accelerator pedal (with overcoming the point of resistance);
- - switch in the "off" position;
- – pressing the switch "0";
- - intervention of the injection computer (in the event of a malfunction or exceeding the maximum allowable speed).
The flashing of the warning light on the instrument panel indicates to the driver that maintaining the set speed impossible.